Process and apparatus for cracking hydrocarbon gases



MM mfiswwmww mmmwaun RE: 29.55% @J mm D N? m mv lL E E q u mm 3 3 U D .uU 2 d m m Q m a v 3 3 .3 anmvawn ufl m. E

March 1932- G. G OBERFELL ET AL PROCESS AND APPARATUS FOR CRACKINGHYDROCARBON GASES Filed May 24, 1928 3 NH. 0 m u a u n w w m a w mm WWINVENTOR 9 L. A13, W l l LFL ATTORNEY '7 Patented Mar. 1, 1932 UNITEDSTATES- PATENT OFFICE GEORGE G. OBERFELL AND FREDERICK E. FBEY, OFBABTLESVHILE, OKLAHOMA, AS-

SIGNOBS TO PHILLIPS PETROLEUM. COMPANY, OF BAB'I'LESVILLE, OKLAHOHA, A

CORPORATION OF DELAWARE PBOCISSAND APPARATUS FOR CRACKING HYDROCABBONGASES Application filed m 24, 1928. Serial m). 280,832.

This invention relates to a process and apparatus a view of reformingsaid gases and producing as a by-product substantial quantities of liuid hydrocarbons of the character of hen- It has heretofore beenproposed to subject hydrocarbons such as occur in natural gas tosuitable temperature conditions and at such velocity as to reform someof the hydrocarbons and convert some of the hydrocarbons into liquidhydrocarbons. In such systems the gases are heated directly orindirectly by products of combustion, and tion the resulting gases andliquids are separated and the liquids are recovered and utilizedindependently of the gases.

Proposals have also been made regarding the recycling of the resultinggases through the reaction steps of the process with a view ofconverting an additional amount of said resulting gases into liquidhydrocarbons, and thereby augmenting the quantity of liquid hydrocarbonsobtained as by-products of the procedure.

The present process differs from the precedin recycling processes inthat the recycle gas and raw gas are not mixed while cold and thentreated but the gases are heated separately; the raw gas to atemperature near the treating temperature and the recycled gastemperature,

to a temperature higher than the treating and then mixed. In this casethe treated or recycled gas acts as a heating medium for the raw gas.

As the raw gas is not heated to a reaction temperature in the heatingtubes, no reaction takes place until the two gases are mixed in thereaction chamber. This prevents the formation of tar and carbon in theheating tubes, and results in a greater yield of benzol and less expensefor cleaning and replacing tubes.

In this process a portion of the treated gas that has been stripped ofits benzol, is recycled to a furnace where it is heated to a temperatureabove the desired treating temperature of the raw gas, and then thissuperheated reformed gas is used to heat the raw gas upto the treatingtemperature.

This process includes the coo ng, purifyfor cracking hydrocarbon gaseswith.

after the reacline (8) ing, and stripping of the treated gas of henzol;the returning of a gaseous portion to a furnace where it is heated to atemperature above the treating temperature; and then the mixing of thisportion with raw gas which has been preheated in separate heating tubesto a temperature lower than the treating temperature. The two gases aremixed in a reaction chamber, the volume and temperatureof each gas beingcontrolled so that the resulting mixture is at the desired treatingtemperature for a proper time period.

The recycled treated gas may atemperature at which it acts as an mertheating medium or it may be heated to such a temperature fore serving asa heating medium for the raw gas.

The invention is practiced in an apparatus of the type diagrammaticallyillustrated in the accompanying drawing, which shows a side elevation ofthe apparatus.

The apparatus shown in the drawing consists of furnace (A), reactionchamber (B), recuperator and tar collector (C), tar scrubber and gascooler (D), tar catch (E), gas pump (1) condensate collector (G) oilwash tower extraction plant (I), recuperator (J) of furnace (A)recuperator (K) and tar collector (L) of recuperator and tar collector(C).

The flow of gases lows: The raw gas in the process is as folto betreated enters at (1), metered by (2), and passed through line (3) toreducing regulator (4). The gases under a constant reduced pressure passthrough gate (a) to distributing header (5) and through gate (6) totubes (6), where the temperature of the gases is raised considerably.The gases leave tubes 6) through gate (0) are collected in header andpass into line (9). If it is found that the gases may be raised to thedesired temperature farther on in the system, gate (6) and gate (0) maybe closed and gate ((1), which is a bypass on tubes (6), opened,allowing the gases to pass directly from gate (a) through gate (d) andinto line (9). The gases pass from line (9) through gate (e) on to thatit is further reformed be-- be heated to where they enter recuperatorand where the temperature of the raw gases is raised to just the pointbelow reformation.

The gases leave recuperator (K) at (11) pass through line (12) gate (f)and enter reaction chamber (B) at (13). If the temperature of the gasesis raised to the desired temperature in tubes (6), gates (e) and may beclosed and gate (g) opened, allowing the gases to flow directly throughbypass (14) from tubes (6) to reaction chamber (B). The gases enteringreaction chamber (B) at (13) at just below reforming temperature, aremixed with a sutlicient amount of superheated gases entering at (51) toraise the gases to a sufficient temperature to cause them to reform. Thereformed gases leave reaction chamber (B) at (15), pass through gate(12.) into recuperator (K) at (16) and are partially cooled by the flowof raw gases in (K) as previously described. The gases leave (K) at (17)enter tar collector (L) where the heavier tar is collected and theuncondensed gases pass from (L) at (18) through gate into gas cooler (D)at (20). If recuperator (K) is not used the hot gases may pass from (15)through bypass (19) into (D) at (20), gates (h) and (i) being closed andbypass gate (7') being open. The gases passing through (D) are cooled,by water sprays (62) supplied by source (61), and the tar-is condensedand collects in the bottom of (D) where it is drawn off with the waterthrough level control valve at The gases pass from (D) at (21) into tarcatch (E) at (23) through (22) and then through (24) to compressor (F)at (25) where the gases are com pressed and forced through gate (7:)line (27) from (26) into condensate collector (G) at (28), thecondensate being periodically drawn off through (71). The cooledreformed gases under pressure free from any condensate pass fromcondensate collector (G) at (29) through line (30) into oil wash tower(H) at (31) and as the gases pass up through the column counter currentto wash oil, are sprayed at (69), the lower boiling constituents areabsorbed by the oil which collects at the bottom of (H) and is automatically trapped through level control ,valve and from oil wash towerat (63)to recovery plant (I) at (64). The wash oil free fromconstituents of the gases of tower H passes from recovery plant (I) at(65) through automatic differential control meter (67) then through line(68) to oil spray (69) where the oil completes the cycle.

The gases free from heavier constituents pass from oil wash tower (H) atwhere the major portion is released through back pressure controlregulator from line (33) to gas mains at (35). A smaller portion of thegas passes through gate (1) line (36), meter (37), gate (122.), line(38), reducing regulator (39) and line (40) into stack gas recuperator(J) where the temperature of the gas is raised somewhat. The gases passfrom recuperator (J), line (42) distributing header (43), gate (n) intotubes (44) where the temperature is raised considerably more. The gasespass from tubes (44) at (45) and pass at (46) into furnace area (47)where the gases reach a very high temperature. The gases pass fromfurnace (47) at (48) through gate (0) into collection header (49)through line (50), entering the reaction chamber (B) at (51) andsupplying the preheated raw gases with sufliciently high temperature tocause their reformation.

The fuel for furnace (A) is supplied at (52), metered at (53),controlled at gate (12), distributed by header (54), passes throughminor contro gates (q) and enters combustion chambers (59) throughburners (58).

The air to support combustion is supplied at the desired positivepressure by a steam driven positive blower (55) metered at ('56), passesthrough recuperator (57), and enters combustion chambers (59) throughburners (58).

The hot products of combustion pass from combustion chambers (59) intocombustion tunnel (60), upthrough a perforated arch into furnace (47through another perfo-' The temperature prevailing in the reactionchamber should be such as to reform some ofthe gases and convert some ofthe same into a substantial amount of liquid hydrocarbons. Thistemperature will fall in a range from 1250 F. to 1750 F. and the higherthe temperature used the faster should be the passage of the gasestreated through the reaction chamber. The exposure time in the reactionchamber for the reaction products will be within a range of 0.002minutes to 10 minutes.

It has been discovered that the precise way, and rate, at which heat iscommunicated to the gases under treatment greatly affects the efficiencyof the process, and an important feature of the invention consists inkeeping the temperature of the raw gases at, or slightly below thetemperature of reaction until they are introduced in the reactionchamber itself. This is accomplished by raising the raw gaws toapproximately the temperature of reaction outside the chamber and thatof the recycled gases to the necessary degree of super-heat to establisha correct common temperature of reaction when the two are combined inthe reaction chamber as explained.

)Vhile a preferred embodiment of the invention has been disclosed, itwill be apparent to those familiar with such processes and paratus thatchanges may be made in details disclosed without departing from thespirit of the invention as set forth in the claims.

What is claimed and desired to be secured by Letters Patent is:

. thereby raising 1. In a process for the pyrolytic conversion ofnormally gaseous aliphatic hydrocarbons to crude benzol, continuouslpassing said gaseous hydrocarbons throug an elongated passageway ofrestricted cross-sectional area while heating the same to a temperaturejust below the conversion temperature of said then passing the gaseoushydrocarbons,

hydrocarbonsthrough an enheated gaseous larged zone of greater crosssectional area than said passageway, passing previously treated residualgas through a second elongated passageway of restricted cross-sectionalarea while continuously heating the second passageway. to a temperaturegreater than said conversion temperature, commingling in said zone saidgaseous aliphatic hydrocarbons with the residual gas discharged from thesecond passageway and the temperature of the hot gaseous aliphatichydrocarbons to a conversion temperature between 1250 and 1750 F., andthen separating the crude benzol so produced. r

2. An apparatus for cracking normally gaseous aliphatic hydrocarbons,with separation and collection of condensates and residual gas,presenting the combination of a heating furnace provlded withindependent sets of heating tubes, one for raw gas and another forretreating residual gas, a reaction chamber, means for introducing boththe heated gases into the reaction chamber, means for withdrawing thetreated mixture from the reaction chamber and means for separating theliquids and gases formedin the reaction chamber with provisions forconducting a residue of the gases formed to be retreated into the one ofsaid independent tube sets for retreating residual gas.

- GEORGE G. OBERFELL.

FREDERICK E. FREY.

iii

controllably

